Land Rover Repair: RR hydraulic cam lifters, hydraulic lifter, rocker shafts

Question
I have a 2002 RR 4.6 HSE with 75,000 miles. During a recent service at the Landrover dealership the Technician noted on the records that CAM/LIFTERS WEARING-MAY CAUSE FUTURE PROBLEMS. Is this a common problem ?, I have extended warranty that runs out in a couple weeks, however the dealership states that this is "normal wear" and is therefore not covered under the warranty. How do you measure the CAM wear, and does Landrover publish wear limits above which the wear would be considered abnormal. Any information would be very much appreciated

Answer
Usually the rapping noise technician pick up is caused by the rocker shafts, not the lifters.  It's actually pretty unusual for the lifters themselves to go bad.  There is not much way to measure a hydraulic lifter though you can pull the intake and check the cam for visible wear.  before that, though, i'd suggest checking the steel cups in the aluminum rocker arms for looseness.